Flare Gas Reduction by Connecting the Flash Gas Compressors as series

The outlet regeneration gas of two mercaptan removal units in South Pars Gas Complex, Phase ۱, with a total flow rate of ۲۰۰۰۰ Nm۳/hr (۱۰۰۰۰ Nm۳/h in each unit), was sent to the boiler fuel gas knock out drum. ۷۰۰۰ Nm۳/hr of it was used as fuel gas in boilers, and the rest with a flow rate of ۱۳۰۰۰ Nm۳/hr was sent to flare. In this paper, investigations including operational tests and dynamic simulations were done to prevent the flaring of regeneration gas as the main flaring source and feed loss in the plant. This goal was achieved by recycling the regeneration gas and switching it from the flaring system to the production line via flash gas compressors. Therefore, Low Pressure - Medium Pressure (LP-MP) flash gas compressors of the running flash gas unit were connected to MP flash gas compressors of the standby unit as series. The new LP-MP-MP configuration was able to handle all the regeneration gas of one gas train. By making this modification, flaring gas was decreased from ۱۳۰۰۰ Nm۳/hr to ۲۲۵۰ Nm۳/hr. One flare stack was turned off. CO۲ and CH۴ emissions to the environment were decreased by ۷۵% on average compared to the design case.

Keywords:

Mercaptan removal unit (MRU) , Flash gas compressors , Regeneration gas , Flaring , Greenhouse gas emission